Introduction; General; For More Information - Buell 2008 XB SERIES Electrical Diagnostics Manual

DYNAMIC DIGITAL FUEL INJECTION (DDFI)

INTRODUCTION

PART NUMBER
HD-44750 DIGITAL TECHNICIAN
The Buell Dynamic Digital Fuel Injection (DDFI) System
provides microprocessor-based electronic engine management
for the 984cc and 1203cc high performance engines. The DDFI
system has the following features:
Independently mapped spark and fuel control.
Engine and air temperature compensated fuel delivery.
Engine load measurement through throttle position.
Single point spark delivery (no waste spark).
Sequential port indirect (manifold) fuel injection.
Open/closed-loop air/fuel control.
Automatic enrichment at start-up.
Electric cooling fan for improved thermal management.
Engine speed position determined using a single sensor
Crankshaft Position (CKP) Sensor.
Engine idle speed managed electronically with idle air
control (IAC) motor.
Full diagnostic capability compatible with the DIGITAL
TECHNICIAN (Part No. HD-44750).
Returnless fuel system (excess pressure relieved in tank
by Fuel Pressure Regulator Valve).
Interactive muffler control with muffler valve position
feedback for 1203cc engines only.
The DDFI system uses ten sensors to monitor the operating
conditions of the engine and make decisions as to ignition and
starter enable, spark and fuel delivery. These sensors are:
Throttle Position (TP) sensor.
Crankshaft Position (CKP) sensor.
Engine Temperature (ET) sensor.
Intake Air Temperature (IAT) sensor.
Oxygen (O ) sensor.
2
Bank Angle Senor (BAS).
Side stand sensor.
Clutch switch.
Neutral switch.
Vehicle speed sensor.
2-2 2008 Buell XB Diagnostics: Engine Management
TOOL NAME
The DDFI system also analyzes how the engine performs
during a ride. It then stores his information internally so it will
be available for the next ride
The 1200 models utilize an interactive exhaust system which
has an electronically controlled actuator that activates a but-
terfly valve that controls exhaust flow in the dual-chamber
muffler. The Electronic Control Module (ECM) monitors engine
speed and throttle position while activating the valve. See
2.33 DTC P1470 (21), P1471 (21), P1477 (21), P1478

GENERAL

The Buell DDFI operates both as an open and closed loop
system which allows it to adjust for all possible operating con-
ditions. During open loop operation, the system utilizes pro-
grammed fuel and spark maps in the ECM which provide ease
of cold starting and maximum power at wide open throttle
(WOT).The adaptive fuel value which is "learned" during closed
loop operation is applied during open loop operation to adjust
fuel and spark maps for optimum performance.
During closed loop operation, the system relies on input from
the O sensor to provide for the optimal air fuel mixture which
2
results in reduced emissions, good fuel economy and power.
In order for the system to enter closed loop operation, the fol-
lowing conditions must be met:
O Sensor at operating temperature (Engine at normal
2
operating temperature).
Operation below 4000 RPM with engine under steady or
light load conditions.
By using both open and closed loop systems, engine perform-
ance is continuously tuned to compensate for changing condi-
tions and provide maximum performance.

FOR MORE INFORMATION

To learn more about the Buell DDFI system, read the following
topics in this section. A system diagram can be found in
Figure 2-1.
Troubleshooting
2.3 DIAGNOSTIC INTRODUCTION
2.4 CHECKING FOR TROUBLE CODES
2.5 CHECK ENGINE LAMP DIAGNOSTICS
2.8 INITIAL DIAGNOSTIC CHECK
Table 2-13
2.2
(21).